Tissue paper making machine, tissue paper produced therewith and method for producing such a tissue paper

ABSTRACT

A tissue paper making machine, a tissue paper product, and a method for producing such a tissue paper product. According to the invention, a dewatering and sheet-forming wire ( 13;14 ) is deposited in the pulp flow area by a texturing wire ( 16;17 ) that is provided with a texture comprised of closed wire zones. This results in the production of a tissue paper product having improved optical and haptic properties.

FIELD OF THE INVENTION

[0001] The invention relates to the production of tissue paper, findingapplication, for example, as kitchen towels, paper handkerchiefs,facials, toilet tissue, napkins and the like.

PRIOR ART

[0002] A wide variety of methods and machines is known with which suchtissue papers can be produced in the sense of a more textile-likecharacter, good absorptivity, especially good wet and dry tear strength,softness and the like, all of which require no detailing. Reference ismade, however, to the German laid-open patent DE-OS 1 461 082 describinga method of making tissue paper having zones differing in basis weight.To block dewatering a modeling wire is placed on the dewatering wire.Both wires have the same extensibility and same roller guidance. Theproduct produced therewith contains, in addition to the sheeting, astructure embossed by the modeling wire, resulting in comparativelysharply defined areas differing in basis weight. The fibers are orientedin the tissue paper with no preferential direction. When crumpled inuse, tissue paper having conventionally a homogenous basis weight overits full surface area forms comparatively long creases which presentadded resistance to the deforming force.

SUMMARY OF THE INVENTION

[0003] The invention is based on the technical problem (objective) ofproviding a machine and a method permitting the achievement of tissuepaper having enhanced visual and haptic properties.

[0004] This objective is achieved in accordance with the invention by atissue paper machine as set forth in claim 1 as well as by a method asset forth in claim 14.

[0005] With the achievement in accordance with the invention a tissuepaper can now be produced which by creating structures of a textilenature conveys an improved visual appearance and “haptic impression”,meaning the impression imparted subjectively as sensed by the fingers,i.e. the “feel”. What is appreciated particularly is a good combinationof surface softness and crumple softness. This is achieved by forming atissue paper textured in small areas of elevated and diminished basisweight in the macro range. The areas of diminished basis weight offerless resistance to a deforming force than the areas of elevated basisweight in thus shortening the length of the creases resulting fromcrumpling. The meaning of this is enhanced crumple softness bothphysically and sensorically.

[0006] It is via the closed wire zones or wire mesh of the backingtexturing wire that dewatering by the sheet-forming wire in the Zdirection is inhibited or strongly restricted, resulting in an addedfiber concentration in the zones of unrestricted dewatering.

[0007] In the tissue paper product a comparatively vapid transitionmaterializes between areas of high basis weight and areas of lower basisweight which is to be evaluated positive as regards the visualappearance of the product without having any negative effect on theenhanced crumple softness intended. The zones differing in basis weightthat form substantially the sole structuring feature. The fibers in thetissue paper permit identifying an orientation in the machiningdirection. All conventional materials can come into consideration forthe wires, e.g. metal-wire or plastics wires. One objective of theinvention is to produce sheet paper not taking on the structure of thewire contacting the paper.

[0008] Further advantageous aspects read from the sub-claims. If thebacking wire structure is designed so that the backing texturizing wirecan be mechanically (preferably hydraulically) lifted from thedewatering and sheet-forming wire, the machine is able to producestandard tissue in addition to texturized tissue paper without anyconversion whatsoever.

[0009] The backing texturizing wire, due to the texture and the wireitself, naturally reduces the overall dewatering capacity and shouldthus be patterned as coarse as possible to minimize detrimenting thedewatering capacity by the backing texturizing wire itself.

[0010] The fineness of the texture in the tissue paper, consisting ofareas differing in basis weight, is limited to the extent with whichblockage of dewatering (due to the texture of the second wire) in the Zdirection is side-stepped by the water transport within thesheet-forming wire in the X-Y direction. For as fine a texture aspossible in the tissue paper the dewatering wire needs to be selected asthin as possible (low water transport in the X and Y direction). Thewires have a wire gauge of 0.1 to 0.4 mm. To avoid lengthy watertransport in the X and Y direction a wire gauge smaller than 0.3 mmshould be employed, smaller than 0.2 mm being even better. It is best toemploy a wire gauge smaller than 0.1 mm.

[0011] In case the dewatering zones are interconnected in thetexturizing wire, the zones of elevated basis weight in the tissue paperare interconnected netted. The resulting influence on the strengths isrelatively slight or none at all. The texturizing wires producing paperwith netted zones of elevated basis weight may also be belts in whichthe supporting fabric is supplemented by some other material which isstructured on the side coming into contact with the paper, examples ofwhich read from EP 0 135 231 B (producing cushions with elevated basisweight) and WO 93/0047A (producing a continuous net with elevated basisweight).

[0012] In case the wire zones of blocked dewatering in the texturizingwire are interconnected, a tissue paper materializes having joined zonesof diminished basis weight, resulting in strengths being detrimented. Inthis case, use can also be made e.g. of a perforated film, belt etc. inaddition to a coarse wire having a closed mesh texture in the concretedesign. Due to the relatively small dewatering zones in the joined zonesof diminished basis weight the stock concentration is high. This resultsin a “cushioning effect” positively influencing the thickness andabsorptivity of multi-ply products (e.g. as the middle ply in three-plykitchen towel, as the bottom ply in two-ply products, the side with thecushioning facing inwards).

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Attached are drawings in which

[0014]FIG. 1a is a diagrammatic illustration of one embodiment of a headbox section and main dewatering section of a tissue paper machine;

[0015]FIG. 1b is a diagrammatic illustration of another embodiment asshown in FIG. 1a;

[0016]FIG. 1c is a diagrammatic illustration of a further embodiment asshown in FIGS. 1a and 1 b;

[0017]FIGS. 2a and 2 b are each illustrations of part of a texturizingwire having interconnected dewatering zones; and

[0018]FIGS. 3a and 3 b are each illustrations of part of a texturizingwire in which the zones blocking dewatering are interconnected.

DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0019] Referring now to FIG. 1a there is illustrated diagrammatically asheet-forming section of a paper machine. Provided in the head boxsection 10 is a stock infeed gap 11 and a dewatering and forming (sheetforming) roll 12. The stock infeed gap 11 in this arrangement is formedby an inner dewatering and sheet-forming wire 13 and an outer dewateringand sheet-forming wire 14 guided differing in extensibility aboutdiverse guide rolls 15 whilst being guided about part of thecircumference of the dewatering and forming roll 12. Sheet-forming takesplace between these two wires. At the side facing away from thesheet-forming section the dewatering and sheet-forming wire 14 is backedby a texturizing wire 16 provided textured and the dewatering andsheet-forming wire 13 is backed by a texturizing wire 17 providedtextured. These texturizing wires too, preferably differ inextensibility in being guided over guide rolls 18, they also featuringan extensibility differing to that of the corresponding dewatering andsheet-forming wire in each case and are guided over separate guiderolls, as evident from FIG. 1a. This makes it possible to lift thetexturizing wire from the dewatering and sheet-forming wire, preferablyhydraulically, without involving any major conversion. Most of the waterpasses the dewatering and sheet-forming wire 14 and texturizing wire 16so that lifting in the case of the texturizing wire 16 would not be ofadvantage.

[0020] Where in agreement, FIG. 1b showing the modified embodimentindicates the same reference numerals as FIG. 1a. In this case atexturizing wire 16 is assigned only to the dewatering and sheet-formingwire 14, since dewatering is done substantially via the dewatering andsheet-forming wire 14.

[0021] In the embodiment as shown in FIG. 1c, a head box 9 is providedfrom which the stock is deposited in the direction of the arrow 10 on ahorizontally oriented dewatering and sheet-forming wire 13′. Over acertain distance the dewatering and sheet-forming wire 13′ is backed bya texturizing wire 17′.

[0022] Referring now to FIGS. 2a, 2 b, 3 a and 3 b there is illustratedhow the texturizing wire comprises dewatering wire zones 19 and wirezones 20 blocking dewatering, it being these zones which, depending onthe specifications and particular application, may be patterned highlydiversely. In FIGS. 2a and 2 b the dewatering zones 19 areinterconnected in a net-like manner. In FIGS. 3a and 3 b the zones 20blocking dewatering are interconnected in a net-like manner. As alreadydiscussed above, this results in the differences as described.

[0023] Via the closed wire zones of the texturizing wires dewatering bythe sheet-forming wire in the Z direction is inhibited or stronglyrestricted, resulting in an added fiber concentration in the zones 19 ofunrestricted dewatering. For as fine a texture as possible in the tissuepaper the dewatering and sheet-forming wire needs to be selected as thinas possible to achieve a low water transport in the X and Y direction.

[0024] Backing by a texturizing wire in the scope as shown is in theregion of the main dewatering zone, i.e. in the transition from fibersuspension to fiber web with a stock density >10%.

1. A tissue paper machine comprising a head box section, a dewateringand sheet-forming section and a drying section, wherein a dewatering andsheet-forming wire (13;14) in the head box section or in thesheet-forming section is backed by a texturizing wire (16;17) providedwith a texture of closed wire zones (20).
 2. The tissue paper machine asset forth in claim 1, characterized in that an outer and/or innerdewatering and sheet-forming wire (13;14) is backed by a texturizingwire (16;17).
 3. The tissue paper machine as set forth in claim 1,characterized in that the texturizing wire (16;17) backs the maindewatering zone, i.e. in the transition from fiber stock suspension tofiber web with approx. >10% stock density.
 4. The tissue paper machineas set forth in claim 3, characterized in that the texturizing wire(16;17) backs the region of a dewatering and forming roll (12).
 5. Thetissue paper machine as set forth in claim 1, characterized in that thetexturizing wire (16;17) can be mechanically lifted from the dewateringand sheet-forming wire (13;14).
 6. The tissue paper machine as set forthin claim 1, characterized in that the texturizing wire (16;17) ispatterned relatively coarse.
 7. The tissue paper machine as set forth inclaim 1, characterized in that the dewatering and sheet-forming wire(13;14) is designed for a low water transport in the X and Y direction.8. The tissue paper machine as set forth in claim 7, characterized inthat the dewatering and sheet-forming wire (13;14) is relatively thin.9. The tissue paper machine as set forth in claim 1, characterized inthat in the texturizing wire (16;17) the dewatering zones (19) areinterconnected at least in part.
 10. The tissue paper machine as setforth in claim 1, characterized in that in the texturizing wire (16;17)the wire zones of blocked dewatering are interconnected.
 11. The tissuepaper machine as set forth in claim 1, characterized in that thetexturizing wire (16;17) and the dewatering and sheet-forming wire(13;14) have separate roll guides (15;18).
 12. The tissue paper machineas set forth in claim 1, characterized in that the texturizing wire(16;17) and the dewatering and sheet-forming wire (13;14) have differentextension.
 13. The tissue paper machine as set forth in claim 1,characterized in that when two texturizing wires (16;17) are provided,the pattern of two texturizing wires (16;17) is disposed either repeatedor offset.
 14. The tissue paper machine as set forth in claim 1,characterized in that in the head box section or in the sheet-formingsection two dewatering and sheet-forming wires (13;14) are provided,each of which is backed by a texturizing wire (16;17).
 15. A method ofproducing a tissue paper product comprising the following steps:depositing the fiber stock suspension on a dewatering and sheet-formingwire (13;14) backed by a structure wire (16;17) consisting of a textureof closed wire zones; inhibiting or strongly restricting dewatering bythe dewatering and sheet-forming wire in the Z direction via the closedwire zones (20) and boosting the concentration of the fibers in thezones (19) of unrestricted dewatering.